High oil pressure intermittently

[skunk0526]

Hey all! Just fixed my trans cooling lines now my oil pressure is all over the place. Only when hot. It idles at about 20 psi but when i give it any throttle at all it shoots to 80 and stays pegged till i let off and the idle goes down. It use to stay at 40-60 when hot.

Should i be concerned?

[MadMikeZ28]

Change your sender. May just be a fluke thing that it happened after the tranny cooler lines.

Or you really screwed something up!

[skunk0526]

I finally drove it around the block a little while ago, and it's pegged at 80 from first crank.
Where is the sending unit located on a 93 blazer? I searched it and most of the replies were for nomas.

[MadMikeZ28]

Usually in one of two places. Next to the distributor or down by the oil filter. I'm gonna say near the dizzy on yours. Its always in the hardest place to get too

[skunk0526]

found it. Was going to order one but i want to be sure its not just the sensor,(which i also can't find) so i'm gonna pick your brain a little more if you don't mind.

Drove it to work this morning 80psi cold. took it on the highway. as i was getting off the exit ramp and let off the gas, pressure goes down, but back up when i give it gas. pulled into a gas station and let it idle.

idled at 40 then down to 20, check engine light came on. then idled between 40 & 20, sounded like stalling when at 20 but when it came back up to 40 it idled fine.

I know these are both inexpensive parts, but moneys a little tight.

Thanks again for all the info.

[swazo]

Quote: Originally Posted by skunk0526

found it. Was going to order one but i want to be sure its not just the sensor,(which i also can't find) so i'm gonna pick your brain a little more if you don't mind.

Drove it to work this morning 80psi cold. took it on the highway. as i was getting off the exit ramp and let off the gas, pressure goes down, but back up when i give it gas. pulled into a gas station and let it idle.

idled at 40 then down to 20, check engine light came on. then idled between 40 & 20, sounded like stalling when at 20 but when it came back up to 40 it idled fine.

I know these are both inexpensive parts, but moneys a little tight.

Thanks again for all the info.

I read on here that you can tell when the oil pressure switch is bad. Let it warm up and unplug the fuel pump relay, if it dies then the oil pressure switch is bad. I confirmed this lastnight on my '90 Blazer.

[skunk0526]

Quote: Originally Posted by MadMikeZ28

Usually in one of two places. Next to the distributor or down by the oil filter. I'm gonna say near the dizzy on yours. Its always in the hardest place to get too

Thought i found it.(Haynes tells me the sending unit is above the oil filter, chiltons makes no mention of it that i could find, but tells you where the switch is, behind the engine) i don't see anything even remotely similar. take a look.

passenger side engine rear. reconnected vacuum lines that were disconnected for some reason (short vac hose that goes into the block is dry rotted in half anyway and need to change. Could that have been part of my problem?) Don't see sending unit or switch.

above oil filter...... nothing

driver side rear.... couldn't spot it.
AM I BLIND!?

[skunk0526]

Just realized my Haynes is for full size Blazer. My bad.

Apologies if I upset anyone at Haynes.

[skunk0526]

It's still under the distributor, engine rear, and I don't see it.

[skunk0526]

Just took it for a drive. Pinned at start, then normal at idle when i got back. 30.

[swazo]

Look at my thread in the 4.3L forum. I have pics and info that should put you in the right direction to find it. If you see where the little fitting with the oil line coming off of it, that's where the oil pressure switch should be. (had an aftermarket gauge, and I reverted back to the oem setup lastnight) http://www.s10forum.com/forum/f107/hard-start-419805/

[MadMikeZ28]

Is it my imagination or is that a 2.8 valve cover???
Don't look at the remote filter. Look at where the filter would be on the motor. Follow the remotes lines to its location. And if it was near the distributor it would be on the driver's side right along the edge where the intake seals to the block between the heads.

[skunk0526]

Finally Found it. Right on Mad Man. Correct me if im wrong if this isn't it. But i assume i need a special socket to get it off after i unplug it.



The oil sending unit still eludes me. Here's a pic of my engine and maybe it will be familiar to you guys.



The only thing close ive seen are the 2 compression joints in this pic.

[skunk0526]

ummm...... Im gonna put myself out there for ridicule. Checked the oil cold just now and it seems there is WAY to much oil. Could that be the answer that my idiocy was to blind to see?!

I hope its just that easy.

[MadMikeZ28]

Yes there is a special socket for the senders. Sometimes when they are is the right location some good pliers will work.
I can not imagine too much oil giving too high a pressure. Pressure will be the same. Too low may give less because of the missing volumn of oil and empty space that would be there.

Now that pic makes sense. It threw me at first with a cover looking thing and the bolt in the back. It did have the wrong lip for a 2.8 cover but I brain locked and could not think of what else it could be. :P

[skunk0526]

sooooo. sender & pressure switch are one and the same? I'm still racking my brain searching for this sender. I'm picking up the switch & socket after work. I have to resolve this soon because on my way to work today, it started running rough and hesitated really bad just at idle. kinda like my one of my calipers was locked up. I just dont want to destroy it on my way home, if its not getting enough oil. It was strugglin for the first time. kind of a low grinding sound.

I'm getting nervous here. Its my daily driver

Thanks for all the info

[skunk0526]

Just finished up. Found out Sender & Switch ate same Sh*t. Spent $20 bucks on the sender & $10 bucks on the socket. and... the old switch breaking clean in half!
all in all, well worth it for these results:

Thank you everyone for their input but mike was right on from the get go.
Didn't know their was no difference in the 2 terms.
Runs like a charm so far.

Swazo:.... It seems that plug is suppose to go to the switch/sending unit under the dizzy.

[skunk0526]

I'm keeping the faith, but it's been one thing after another.
All these forums (and contributors) have to offer has been a lifesaver! So.... Im not so worried anymore.

Thanks again everyone.

[MadMikeZ28]

Well you were busy yesturday! Got it done though, thats good.
Sender, switch, sensor... They are just as different as a violin and a fiddle. It somewhat depends on where you come from.

[skunk0526]

Changed the oil last night and shooting up to like 70 when given throttle, 60 at idle. because of the oil change maybe? I'm hoping it levels out. No CES though, that's always a plus. However........

Brakes shuttering badly when stopping. Even do it when i'm cruising at 15 to 20 mph after the break....then it gradually goes away till i break again.

Guess thats for a different thread huh?

Done

[skunk0526]

just got a ces code on my last trip. checked it out and it read pressure switch, and coolant temp sensor. which i replaced a few months ago. guess they just need to be cleared as i've done both.

disconnected the battery for a min & backed it into the garage. no codes.... yet.

The higher pressure at start, and pinned at acceleration (then drops to 70) is still bothering me though.

I'll see how she runs tomorrow..

[MadMikeZ28]

The codes will stay and a light come on occasionaly until cleared, even after the item(s) fixed.
The high pressure, with digital, I would not imagine it being the gauge. When you changed the oil did you use a new filter of the same brand? Only other thing I can think of is the btpass in the oil pump stuck. Its hard too imagine because it spends its life in lubrication but I have heard of them getting stuck.
Maybe warped rotors